At present, when a fire is detected in an aircraft, for example, by a passenger seeing or smelling a fire, or smoke, a hand extinguisher is used to suppress the fire. Currently, flight attendants in an aircraft follow guidelines in the event of a fire or overheat situation. Hidden fires may occur in areas that are not visible or relatively inaccessible. In such situations smoke or fumes may be produced in one area but may be seen emanating from an aperture, or gap into the cabin some distance away. The guidelines state that the flight attendants may need to locate hotspots that are indicative of the location of a fire, by feeling along cabin surfaces with the back of the hands. Fire-extinguishing agent is then directed onto the fire via ventilation holes in the panels, if present, or the panels may need to be removed or cut to provide local access.
Distributed temperature sensors, such as fibre optics have also been used to detect fires in aircraft. Such distributed temperatures are capable of providing information on the position of a temperature excursion. US 2005/0089081 A1 describes a method for detecting and signalling the existence of overheating conditions and fires in an aircraft, such as in the event of a rupture or leak of the pipe system that carries the hot bleed air from the aircraft engines to the end user devices such as air conditioning packs. The temperature increase and its spatial location are detected by means of a sensor comprising a fibre optic cable and the corresponding sensor signal is provided to a computer for evaluation. This information can be indicated to the flight crew or maintenance personnel by a corresponding display or read-out from the computer.
U.S. Pat. No. 5,467,942 describes a high accuracy light radar, fibre optic temperature sensing system for use in an aircraft such as a helicopter. An optical sensing system simultaneously obtains absolute temperature measurements from various locations in the aircraft while measuring the position of one or more displaceable elements. A plurality of position values associated with respective positions of the displaceable objects and temperature values associated with the temperatures at the plurality of locations are then outputted to the flight controller which then processes this information and outputs appropriate commands to control the actuators of the aircraft.